repetitive strain injuryn. Abbr. RSI Damage to tendons, nerves, and other soft tissues that is caused by the repeated performance of a limited number of physical movements and is characterized by numbness, pain, and a wasting and weakening of muscles.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.repetitive strain injury or repetitive stress injuryn (Pathology) a condition, characterized by arm or wrist pains, that can affect musicians, computer operators, etc, who habitually perform awkward hand movements. Abbreviation: RSI Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014